Propionibacterium spp. are part of the normal skin flora and often considered non pathogenic. Most published reports about Propionibacterium spp. have involved acne vulgaris and healthy persons (Gehse et al. (1983) Arch. Dermatol. Res. 275(2): 100-104). However, they may cause significant infections, particularly after implantation of a foreign body, such as a prosthetic valve, intraocular lense, ventriculoperitoneal shunt, or orthopedic implant (Jakab et al. (1996) Yale J. Biol. Med. 69(6): 477-482). In particular, Sperling et al. reported that Propionibacterium spp. account for 16% of prosthetic shoulder infections (Sperling et al. (2001) Clin. Orthop. Relat. Res. 382: 206-216). Franta et al. reported that among 31/282 patients (11%) with unsatisfactory shoulder arthroplasties, positive intraoperative cultures were found in 23 at the time of revision surgery, with the most common organisms isolated being coagulase-negative Staphylococcus spp., followed by P. acnes (Franta at al. (2007) J. Shoulder Elbow Surg. 16: 555-562). Indeed, P. acnes is emerging as an important pathogen in orthopedic implant infections (Brook et al. (1991) Rev. Infect. Dis. 13:168-172; Lutz et al., (2005) Eur. J. Clin. Microbiol. Infect. Dis. 24: 739-744) with persistent pain reported as the major symptom. P. acnes is a Gram-positive bacterium, developing in anaerobic conditions. This bacterium belongs to the natural human flora, commensale of the skin, the conjunctive tissue, the outer ear, the oral cavity, the high respiratory tractus and occasionally, the intestine and the vagina. P acnes is in particular associated with the inflammatory process in the acneic lesions. This bacterium is also at the origin of post-operative, in particular in the event of presence of implant, potentially severe infections. This bacterium was associated with other aerobic or anaerobic bacteria with dental infections, parodontites, conjunctivites, endophtalmies, cerebral abscesses, empyemes, lung infections, peritonites, osteomyelitis, septic arthritis and endocarditis in particular on prosthesis, and meningitidis on shunts. Development of prosthetic infections begins with colonization of the foreign material, followed by a complex metamorphosis by the microorganisms with resultant biofilm formation. When bacteria grew in matrix enclosed community, they became recalcitrant to antibiotic therapy and insensitive to host defense mechanisms because of some changes in their cellular characteristics. These infections generally occur (70% of the cases) among diabetes patients introducing an immunodepression, cancer patients having undergone a surgical operation or carrying prosthetic material or catheter.
It is estimated that 2, 8 to 12% of the osteo-articular infections result from infections of prosthesis from hip, knee, shoulder (Brook et al. (1991) Rev. Infect. Dis. 13:168-172). Another study showed that a third of arthritis with P. acnes might be due to infections on prosthesis (Brook et al. (1993) Am. J. Med. 94:21-28). The mechanisms of contamination of the operational wound are probably contaminations by the cutaneous flora of the patient, or an airborne contamination (patient or surgical team). It could be related to a hypothetical persistence on surfaces. Insufficiency of the treatment of air in intervention room has been shown as a factor of infection of the operational site in orthopedy. (Berthelot et al. (2006) Infect. Control. Hosp. Epidemiol. 27:987-990).
Clinical symptoms are rarely sufficient to ascertain the infection. In the vast majority of cases, patients are paucisymtomatic. The gold standard for diagnosing prosthesis infections remains bacteriological analysis, which involved isolation and culture of the infecting bacteria at the site of infection, from relevant samples. Bacteriological analysis is generally considered as significant if at least 2 samples taken during the surgery are positive for P. acnes. Ultrasound-guided needle aspiration or image-guided core-needle biopsy can also be carried.
Several drawbacks are however associated to bacteriological analysis. The culture is slow and difficult under anaerobic conditions, often requiring 48 hours before the appearance of the colonies. Thus, it is advised to preserve the cultures during 5 days, sometimes the culture can last 15 to 20 days. Other anaerobic bacteria are often found during the cultures. Indeed, the specificity is often insufficient, since contaminant microorganisms may be isolated, rending the diagnosis of P. acnes infections more difficult. The difficulty of diagnosis in the case of plurimicrobial infections lies in the fact that it is necessary to resort to various selective mediums. In addition, P. acnes is a common contaminant of hemocultures.
According to various studies (Brook et al. (1991) Rev. Infect. Dis. 13:168-172; Lutz et al. (2005) Eur. J. Clin. Microbiol. Infect. Dis. 24: 739-744), the contamination cases can go from 17 to 88%, which increases the risk of appearance of false-positive results. Thus in addition to clinical data, the number of positive cultures as well as the results of the direct examination of the patient must be taken into account for the diagnosis of P. acnes infection. The probability of infection increases with the number of positive samples.
There are currently no other methods for establishing the diagnosis of P. acnes prosthesis infection. Thus the object of this invention proposes an alternative technique for the diagnosis of the P. acnes infections. A serological approach based on the antibodies of anti-P. acnes could overcome the drawbacks associated to bacteriological analysis.